Obesity

Overweight and obesity are both labels for ranges of weight that are greater than what is generally considered healthy for a given height. The terms also identify ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.

Definitions for Adults

For adults, overweight and obesity ranges are determined by using weight and height to calculate a number called the “body mass index” (BMI). BMI is used because, for most people, it correlates with their amount of body fat.

An adult who has a BMI between 25 and 29.9 is considered overweight.

An adult who has a BMI of 30 or higher is considered obese.

It is important to remember that although BMI correlates with the amount of body fat, BMI does not directly measure body fat. As a result, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat. For more information about BMI, visit Body Mass Index.

Other methods of estimating body fat and body fat distribution include measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic resonance imaging (MRI).

For children and teens, BMI ranges above a normal weight have different labels (overweight and obese). Additionally, BMI ranges for children and teens are defined so that they take into account normal differences in body fat between boys and girls and differences in body fat at various ages.

Assessing Health Risks Associated with Overweight and Obesity

BMI is just one indicator of potential health risks associated with being overweight or obese. For assessing someone’s likelihood of developing overweight- or obesity-related diseases, the National Heart, Lung, and Blood Institute guidelines recommend looking at two other predictors:

The individual’s waist circumference (because abdominal fat is a predictor of risk for obesity-related diseases).

Other risk factors the individual has for diseases and conditions associated with obesity (for example, high blood pressure or physical inactivity).

For more information about the assessment of health risk for developing overweight- and obesity-related diseases, visit the following Web pages from the National Heart, Lung, and Blood Institute:

Research has shown that as weight increases to reach the levels referred to as “overweight” and “obesity,”* the risks for the following conditions also increases:

Coronary heart disease

Type 2 diabetes

Cancers (endometrial, breast, and colon)

Hypertension (high blood pressure)

Dyslipidemia (for example, high total cholesterol or high levels of triglycerides)
Stroke

Liver and Gallbladder disease

Sleep apnea and respiratory problems

Osteoarthritis (a degeneration of cartilage and its underlying bone within a joint)

Gynecological problems (abnormal menses, infertility)

*Overweight is defined as a body mass index (BMI) of 25 or higher; obesity is defined as a BMI of 30 or higher. For more, see Defining Obesity.

Trends in the United States

Obesity is defined as a body mass index (BMI) of 30 or greater. BMI is calculated from a person’s weight and height and provides a reasonable indicator of body fatness and weight categories that may lead to health problems. Obesity is a major risk factor for cardiovascular disease, certain types of cancer, and type 2 diabetes.

During the past 20 years there has been a dramatic increase in obesity in the United States. In 2008, only one state (Colorado) had a prevalence of obesity less than 20%. Thirty-two states had a prevalence equal to or greater than 25%; six of these states (Alabama, Mississippi, Oklahoma, South Carolina, Tennessee, and West Virginia) had a prevalence of obesity equal to or greater than 30%.

When it comes to weight loss, there’s no lack of fad diets promising fast results. But such diets limit your nutritional intake, can be unhealthy, and tend to fail in the long run.

The key to achieving and maintaining a healthy weight isn’t about short-term dietary changes. It’s about a lifestyle that includes healthy eating, regular physical activity, and balancing the number of calories you consume with the number of calories your body uses.

Staying in control of your weight contributes to good health now and as you age.

If you’ve been thinking about your current weight, it may be because you’ve noticed a change in how your clothes fit. Or maybe you’ve been told by a health care professional that you have high blood pressure or high cholesterol and that excessive weight could be a contributing factor. The first step is to assess whether or not your current weight is healthy.

How can I tell if I’m at a healthy weight?

Adult Body Mass Index or BMI

One way to begin to determine whether your weight is a healthy one is to calculate your “body mass index” (BMI). For most people, BMI is a reliable indicator of body fatness. It is calculated based on your height and weight.

If your BMI is less than 18.5, it falls within the “underweight” range.

If your BMI is 18.5 to 24.9, it falls within the “normal” or Healthy Weight range.

If your BMI is 25.0 to 29.9, it falls within the “overweight” range.

If your BMI is 30.0 or higher, it falls within the “obese” range.

“Underweight”, “normal”, “overweight”, and “obese” are all labels for ranges of weight. Obese and overweight describe ranges of weight that are greater than what is considered healthy for a given height, while underweight describes a weight that is lower than what is considered healthy. If your BMI falls outside of the “normal” or Healthy Weight range, you may want to talk to your doctor or health care provider about how you might achieve a healthier body weight. Obesity and overweight have been shown to increase the likelihood of certain diseases and other health problems.

At an individual level, BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual. A trained healthcare provider should perform appropriate health assessments in order to evaluate an individual’s health status and risks.

Waist Circumference

Another way to assess your weight is to measure your waist size. Your waistline may be telling you that you have a higher risk of developing obesity-related conditions if you are:

A man whose waist circumference is more than 40 inches

A non-pregnant woman whose waist circumference is more than 35 inches

Excessive abdominal fat is serious because it places you at greater risk for developing obesity-related conditions, such as Type 2 Diabetes, high blood cholesterol, high triglycerides, high blood pressure, and coronary artery disease. Individuals who have excessive abdominal fat should consult with their physicians or other health care providers to develop a plan for losing weight.

What is healthy weight loss?

It’s natural for anyone trying to lose weight to want to lose it very quickly. But evidence shows that people who lose weight gradually and steadily (about 1 to 2 pounds per week) are more successful at keeping weight off. Healthy weight loss isn’t just about a “diet” or “program”. It’s about an ongoing lifestyle that includes long-term changes in daily eating and exercise habits.

To lose weight, you must use up more calories than you take in. Since one pound equals 3,500 calories, you need to reduce your caloric intake by 500—1000 calories per day to lose about 1 to 2 pounds per week.1

Once you’ve achieved a healthy weight, by relying on healthful eating and physical activity most days of the week (about 60—90 minutes, moderate intensity), you are more likely to be successful at keeping the weight off over the long term.

Losing weight is not easy, and it takes commitment. But if you’re ready to get started, we’ve got a step-by-step guide to help get you on the road to weight loss and better health.